Image capturing device having continuous image capture

ABSTRACT

Methods, devices, and systems for continuous image capturing are described herein. In one embodiment, a method includes continuously capturing a sequence of images with an image capturing device. The method may further include storing a predetermined number of the sequence of images in a buffer. The method may further include receiving a user request to capture an image. In response to the user request, the method may further include automatically selecting one of the buffered images based on an exposure time of one of the buffered images. The sequence of images is captured prior to or concurrently with receiving the user request.

CROSS-REFERENCED APPLICATION

The present application is related to the following commonly-owned,concurrently-filed application: application publication no. US2010/0309334, filed Jun. 5, 2009, entitled “Camera Image Selection Basedon Detected Device Movement” and is incorporated by reference inentirety herein.

TECHNOLOGY FIELD

At least some embodiments of the present invention relate to imagecapturing devices having continuous image capture.

BACKGROUND

Image capturing devices include cameras, portable handheld electronicdevices, and electronic devices. These image capturing devices typicallyuse a preview resolution for capturing a preview image of a scene.Subsequently, a user provides an input to take a photograph. The deviceswitches from preview resolution to full resolution prior to capturingan image. Switching from preview to full resolution causes a time lag,which may lead to user frustration. Also, camera shake during the timewhen a user presses a button or touches a touchscreen can degrade imagequality.

SUMMARY

Methods, devices, and systems for continuous image capturing aredescribed herein. In one embodiment, a method can include continuouslycapturing images with an image capturing device. The method can includestoring a predetermined number of the sequence of images in a buffer.The device can receive a user request to capture an image. The methodcan automatically select one of the buffered images based on one or moreparameters. For example, the selection may be based on an exposure timeof one of the buffered images and optionally an image quality parameter(e.g., image contrast). Alternatively, the selection may be based onlyon the image quality parameter. The sequence of images can be capturedjust prior to or concurrently with receiving the user request. Themethod can include automatically displaying the selected image on thedisplay of the image capturing device. These operations can be initiatedafter the device enters an image capturing mode or other mode. Forexample, the device may have many functions and capabilities (e.g., thedevice may be a smart phone or personal digital assistant (PDA) whichcan send and receive emails, allow surfing of the internet, createdocuments, and also act as a camera), and a user can place the deviceinto camera mode in order to cause it to begin these continuousoperations. In an embodiment, the device is not continuously performingthese operations when it is not in camera mode.

In an embodiment, the continuously captured images can be captured infull resolution. The sequence of images can be advantageously capturedjust prior to the device receiving the user request for the photographto avoid camera shake associated with the user request (e.g., pressing ashutter button, touching a touchscreen). One of the sequence of imagescan be automatically selected and displayed in full resolution inresponse to receiving the user request.

The present invention can include systems and devices that perform thesemethods, including data processing systems which perform these methods,and machine readable media which when executed on data processingsystems cause the systems to perform these methods.

Other features of the present invention will be apparent from theaccompanying drawings and from the detailed description which follows.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention is illustrated by way of example and notlimitation in the figures of the accompanying drawings in which likereferences indicate similar elements.

FIG. 1 shows a portable handheld device having a built-in digital cameraand a touch sensitive screen in accordance with one embodiment of thepresent invention.

FIG. 2 illustrates a flow diagram of a continuous image capture mode foran image capturing device in accordance with embodiments of the presentinvention.

FIG. 3 illustrates a detailed flow diagram of a continuous image capturemode for an image capturing device in accordance with embodiments of thepresent invention.

FIG. 4 illustrates an exemplary buffer for storing a predeterminednumber of the sequence of images in accordance with one embodiment ofthe present invention.

FIG. 5 shows an image capturing device 2950 in accordance with oneembodiment of the present invention.

FIG. 6 shows an embodiment of a wireless image capturing device inaccordance with one embodiment of the present invention.

FIG. 7 shows a data processing system according to an embodiment of thepresent invention.

DETAILED DESCRIPTION

The following description and drawings are illustrative of the inventionand are not to be construed as limiting the invention. Numerous specificdetails are described to provide a thorough understanding of the presentinvention. However, in certain instances, well known or conventionaldetails are not described in order to avoid obscuring the description ofthe present invention. References to one or an embodiment in the presentdisclosure are not necessarily references to the same embodiment; and,such references mean at least one.

Methods, devices, and systems for continuous image capturing aredescribed herein. In one embodiment, a method includes continuouslycapturing, after entry into an image capturing mode, a sequence ofimages with an image capturing device. The method stores a predeterminednumber of the sequence of images in a buffer. The device receives a userrequest to capture an image. The method automatically selects one of thebuffered images based on one or more parameters. For example, theselection may be based on an exposure time and optionally an imagequality parameter (e.g., image contrast). The sequence of images arecaptured just prior to or concurrently with receiving the user request.The method automatically displays the selected image in full resolutionon the display of the image capturing device.

Advantageously, an image captured prior to a user requesting the captureof an image has an image quality that is not degraded by camera shakeassociated with the user request.

FIG. 1 shows a portable image capturing device 100 having a built-indigital camera in accordance with one embodiment. In this example, theportable device 100 is shown while it is held in the user's hand 107.The device 100 may be an IPHONE device by Apple Inc., of Cupertino,Calif. Alternatively, it could be any other electronic device that has abuilt-in digital camera. The built-in digital camera includes a lens 103located in this example on the back face of the device 100. The lens maybe a fixed optical lens system or it may have focus and optical zoomcapability. Although not depicted in FIG. 1, inside the device 100 arean electronic image sensor and associated hardware circuitry and runningsoftware that can capture a digital image of a scene 102 that is beforethe lens 103.

The digital camera functionality of the device 100 optionally includesan electronic or digital viewfinder for an image capturing mode. In FIG.1, the scene 102 is displayed on the screen. Upon initiation of theimage capture mode, images 97 are continuously captured and displayed onthe screen.

The viewfinder displays live, captured video (e.g., series of images) orimages in full resolution of the scene 102 that is before the camera, ona portion of the touch sensitive screen 104 as shown. In this case, thedigital camera also includes a soft or virtual shutter button whose icon105 is displayed by the screen 104, directly below the viewfinder imagearea. As an alternative or in addition, a physical shutter ornon-virtual button may be implemented in the device 100. The device 100includes all of the needed circuitry and/or software for implementingthe digital camera functions of the electronic viewfinder, shutterrelease, continuous image capturing, storing of a predetermined numberof the sequence of images, and automatic selection of an image based onone or more parameters (e.g., exposure, image quality parameter) asdescribed below.

FIG. 2 illustrates a flow diagram of a continuous image capture mode foran image capturing device in accordance with embodiments of the presentinvention. The image capturing device is initialized at block 202.Initialization includes powering the image capturing device andselecting an image capture mode. In one embodiment, processing logicexecutes the operations of the image capture mode. The processing logicmay include hardware (circuitry, dedicated logic, etc.), software (suchas is run on a general purpose computer system or a dedicated machine ora device), or a combination of both. The processing logic cancontinuously capture images with the image capturing device at block204. The processing logic can store a predetermined number (e.g., 2, 3,4, 5) of the sequence of images in a buffer at block 206. In anembodiment, a new image is captured and stored in the buffer at acertain rate (e.g., 1/15 of a second). The processing logic cancontinuously purge or replace other images in the buffer that werepreviously captured prior to the sequence of images at block 208.

FIG. 4 illustrates an exemplary buffer for storing a predeterminednumber of the sequence of images in accordance with one embodiment ofthe present invention. The buffer 400 includes available memory spaces402-420 for the storing the captured images. A predetermined number(e.g., 3) of the sequence of images are stored in the buffer 400. Theseimages are captured just prior to receiving the user request to take aphotograph. Memory resources can be conserved in that only the sequenceof images are stored with previously captured images being purged.

Returning to FIG. 2, the processing logic can display on a display ofthe image capturing device the continuously captured images at block210. In an embodiment, the continuously captured images are displayedprior to receiving a user request to capture an image at block 212. Theprocessing logic can automatically select one of the sequence of imagesbased on an exposure time and optionally an image quality parameter(e.g., image contrast) at block 214. Alternatively, the selection can bebased only on the image quality parameter. More details regarding theautomatic selection of an image will be described below in conjunctionwith the description of FIG. 3.

In one embodiment, the sequence of images includes only images capturedjust prior to receiving the user request. In one embodiment, thesequence of images does not include images captured after receiving theuser request. In an alternative embodiment, the sequence of images mayinclude images captured before receiving the user request and atapproximately the time of receiving the user request. In anotheralternative embodiment, the sequence of images may include imagescaptured before, during, and/or after receiving the user request.

In one embodiment, the sequence of images is captured just prior toreceiving the user request. The processing logic can automatically storethe selected image in memory and display the selected image on thedisplay of the image capturing device at block 216. The memory may beused to store photos or video in the form of a user-initiated photo orvideo library.

In an embodiment, the continuously captured images and the selectedimage are captured and displayed in full resolution. A user can quicklycapture an image with minimal time lag between sending a request to takea photograph and the capture of the image. The sequence of images areadvantageously captured just prior to the processing logic receiving theuser request for the photograph to avoid camera shake associated withthe user request (e.g., pressing a shutter button, touching atouchscreen).

FIG. 3 illustrates a detailed flow diagram of an automatic selection ofone of the sequence of images in image capture mode for an imagecapturing device in accordance with embodiments of the presentinvention. In some embodiments, automatically selecting one of thesequence of images includes determining an exposure time for one of thebuffered images (e.g., most recently captured image) at block 316. Theprocessing logic can determine whether the exposure time meetspredetermined criteria that is based on a predetermined thresholdexposure time (e.g., 1/100 of a second) at block 318. For example, theprocessing logic can determine whether the exposure time is less than,approximately equal to, or greater than the predetermined thresholdexposure time. In an embodiment, the processing logic determines whetherthe exposure time exposure time meets predetermined criteria (e.g., isexposure time less than the predetermined threshold exposure time). Atblock 320, the processing logic can automatically select the mostrecently captured image, which was captured just prior to receiving theuser request, if the exposure time meets the predetermined criteria.Using the most recently captured image, which is received just prior toreceiving the user request, avoids degrading the image if camera shakeoccurs with the user request.

If the exposure time fails to meet the predetermined criteria (e.g., theexposure time is approximately equal to or greater than thepredetermined threshold exposure time), then camera shake (and thus ablurry image) might be a problem. There is a higher chance that thecamera moves a noticeable amount if the exposure time is longer. Thus,the processing logic can determine a focus score for each captured imagestored in buffer 400 at block 322 if the exposure time fails to meet thepredetermined criteria. Alternatively, a user can select one of thebuffered images if the exposure time fails to meet the predeterminedcriteria.

The focus score may be determined based on image quality parameters(e.g., image contrast, image resolution, dynamic range, color renderingproperties) using an automatic focus mechanism that can perform anautomatic focus scan. This scan positions a lens of the image capturingdevice in various positions. The automatic focus mechanism can obtainfocus scores with each focus score being associated with a respectivelens position of the automatic focus scan. In an embodiment, a focusscore is a scene-dependent measure of contrast. The automatic focusmechanism can determine whether the obtained focus scores for a sceneare acceptable. In an embodiment, a focus area can be automaticallydetermined based on a user selection of a portion of the screen (e.g.,touchscreen) of the image capturing device. Then, the automatic focusscan may be initiated for the focus area. The focus scores for the focusarea may be obtained prior to the operations of FIG. 3. An image sensingunit may send frames of metadata (e.g., focal-number, exposure time,white balance, focus score) to the processing logic. Focus scores areobtained from the metadata.

In one embodiment, the image sensing unit, for each pixel associatedwith a previously determined focus area, can compute the absolutedifference (in RGB values) horizontally and vertically between adjacentpixels. Then, the horizontal and vertical difference values are combinedinto a single number for each pixel by either forming the sum or amaximum of those two. Then, for each scan line of an image sensor, thesepixel values get combined, by either forming the sum or a maximum. Thenthe resulting value from each scan line is combined over the entirefocus area by adding these values to generate a focus score for thecaptured image. A higher focus score indicates a sharper image quality.

In an embodiment, the processing logic can apply weighted factors toeach of the buffered images at block 324. For example, a most recentlycaptured image T1 may have a weighted factor W1 of 1.0, a next mostrecently captured image T2 may have a weighted factor W2 of 0.9, and anext most recently captured image T3 may have a weighted factor W3 of0.83. In this case, the weighted factors are biased towards the imageT1. Alternatively, the weighted factors can be biased evenly or awayfrom T1, the most recently captured image just prior to receiving theuser request to take a photograph.

Next, the processing logic can determine a product of the focus scoreand the weighted factor for each of the respective the sequence ofimages at block 326. For example, the products may include S1*W1, S2*W2,and S3*W3 with S1-S3 being focus scores for the respective the sequenceof images. The processing logic can select a most recently capturedimage having a highest weighted focus score product at block 328 if theexposure time is approximately greater than or equal to thepredetermined threshold exposure time. In one embodiment, the images T2or T3 may be selected over T1 only if a user perceived benefit isachieved. For example, the weighted focus score product for T2 or T3 mayneed to exceed the product for T1 by a predetermined threshold (e.g.,20%) in order to select T2 or T3 rather than T1, which is the mostrecently captured image. The processing logic can automatically displaythe selected image on the display of the image capturing device at block330.

In an alternative embodiment, the processing logic automaticallychronologically displays the sequence of images after receiving a userinput to take a photograph. The user can then select which of thesequence of images is most desired by the user (e.g., highest imagequality, correct subject, etc.). Alternatively, the processing logic candisplay the sequence of images in a prioritized order based on imagequality, focus score, etc.

The operations of the present disclosure can be performed rearranged,deleted, or include additional operations. For example, in anembodiment, the exposure time of one of the buffered images is used toautomatically select one of the buffered images. In this case, no focusscores or weighted factors are needed for selecting one of the bufferedimages. The blocks 322-328 may be replaced with a new operation thatallows a user to select one of the buffered images if the predeterminedcriteria is not met at block 318. Alternatively, the blocks 322-328 maybe replaced or supplemented with motion criteria to automatically selectone of the buffered images. For example, a motion sensor integrated withthe image capturing device may generate motion information for eachcaptured image. This can be used to select an image captured during atime with no or minimal camera shake.

Alternatively, the blocks 316, 318, and 320 may be optionally removed,and the automatic selection is based on focus scores for each bufferedimage. These focus scores may be previously calculated during anautomatic focus scan. In another embodiment, the motion information isused to filter focus scores.

Many of the methods in embodiments of the present invention may beperformed with a digital processing system, such as a conventional,general-purpose computer system. Special purpose computers, which aredesigned or programmed to perform only one function, may also be used.

In some embodiments, the methods, systems, and apparatuses of thepresent disclosure can be implemented in various devices includingelectronic devices, consumer devices, data processing systems, desktopcomputers, portable computers, wireless devices, cellular devices,tablet devices, handheld devices, multi touch devices, multi touch dataprocessing systems, any combination of these devices, or other likedevices. FIGS. 5-7 illustrate examples of a few of these devices.

FIG. 5 shows an image capturing device 2950 in accordance with oneembodiment of the present invention. The device 2950 may include ahousing 2952, a display/input device 2954, a speaker 2956, a microphone2958 and an optional antenna 2960 (which may be visible on the exteriorof the housing or may be concealed within the housing). The device 2950also may include a proximity sensor 2962 and a motion sensor 2964 (e.g.,a gyroscrope, a motion detector, a tilt sensor such as mercury switch, acompass, or any combination thereof) that generates motion information.The device 2950 may be a cellular telephone or a device which is anintegrated PDA and a cellular telephone or a device which is anintegrated media player and a cellular telephone or a device which isboth an entertainment system (e.g. for playing games) and a cellulartelephone, or the device 2950 may be other types of devices describedherein. In one particular embodiment, the device 2950 may include acellular telephone and a media player and a PDA, all contained withinthe housing 2952. The device 2950 may have a form factor which is smallenough that it fits within the hand of a normal adult and is lightenough that it can be carried in one hand by an adult. It will beappreciated that the term “portable” means the device can be easily heldin an adult user's hands (one or both); for example, a laptop computer,an iPhone, and an iPod are portable devices.

In certain embodiments of the present disclosure, the device 2950 can beused to implement at least some of the methods discussed in the presentdisclosure.

FIG. 6 shows an embodiment of a wireless image capturing device whichincludes the capability for wireless communication and for capturingimages. Wireless device 3100 may include an antenna system 3101.Wireless device 3100 may also include a digital and/or analog radiofrequency (RF) transceiver 3102, coupled to the antenna system 3101, totransmit and/or receive voice, digital data and/or media signals throughantenna system 3101.

Wireless device 3100 may also include a digital processing system 3103to control the digital RF transceiver and to manage the voice, digitaldata and/or media signals. Digital processing system 3103 may be ageneral purpose processing system, such as a microprocessor orcontroller for example. Digital processing system 3103 may also be aspecial purpose processing system, such as an ASIC (application specificintegrated circuit), FPGA (field-programmable gate array) or DSP(digital signal processor). Digital processing system 3103 may alsoinclude other devices, as are known in the art, to interface with othercomponents of wireless device 3100. For example, digital processingsystem 3103 may include analog-to-digital and digital-to-analogconverters to interface with other components of wireless device 3100.Digital processing system 3103 may include a media processing system3109, which may also include a general purpose or special purposeprocessing system to manage media, such as files of audio data.

Wireless device 3100 may also include a storage device 3104, coupled tothe digital processing system, to store data and/or operating programsand capture images for the Wireless device 3100. Storage device 3104 maybe, for example, any type of solid-state or magnetic memory device.Storage device 3104 may be or include a machine-readable medium.

A machine-readable medium includes any mechanism for storing ortransmitting information in a form readable by a machine (e.g., acomputer). For example, machines store and communicate (internally andwith other devices over a network) code and data using machine-readablemedia, such as machine storage media (e.g., magnetic disks; opticaldisks; random access memory; read only memory; flash memory devices;phase-change memory).

Wireless device 3100 may also include one or more input devices 3105,coupled to the digital processing system 3103, to accept user inputs(e.g., telephone numbers, names, addresses, media selections, etc.)Input device 3105 may be, for example, one or more of a keypad, atouchpad, a touch screen, a pointing device in combination with adisplay device or similar input device.

Wireless device 3100 may also include at least one display device 3106,coupled to the digital processing system 3103, to display informationsuch as messages, telephone call information, contact information,pictures, images, movies and/or titles or other indicators of mediabeing selected via the input device 3105. Display device 3106 may be,for example, an LCD display device. In one embodiment, display device3106 and input device 3105 may be integrated together in the same device(e.g., a touch screen LCD such as a multi-touch input panel which isintegrated with a display device, such as an LCD display device). Thedisplay device 3106 may include a backlight 3106A to illuminate thedisplay device 3106 under certain circumstances. It will be appreciatedthat the wireless device 3100 may include multiple displays.

Wireless device 3100 may also include a battery 3107 to supply operatingpower to components of the system including digital RF transceiver 3102,digital processing system 3103, storage device 3104, input device 3105,microphone 3105A, audio transducer 3108, media processing system 3109,sensor(s) 3110, and display device 3106, and an image sensor 3159 (e.g.,CCD (Charge Coupled Device), CMOS based device). The image sensor may beintegrated with an image processing unit 3160. The display device 3106may include a Liquid Crystal Display (LCD) which may be used to displayimages which are captured or recorded by the wireless image capturingdevice 3100. The LCD serves as a viewfinder of a camera and there mayoptionally be other types of image display devices on device 3100 whichcan serve as a viewfinder.

The device 3100 also includes an imaging lens 3163 which can be disposedover image sensor 3159. The processing system 3103 controls theoperation of the device 3100; and, it may do so by executing a softwareprogram stored in ROM 3157, or in the processing system 3103, or in bothROM 3157 and the processing system 3103.

The processing system 3103 controls the image processing operation; and,it controls the storage of a captured image in storage device 3104. Theprocessing system 3103 also controls the exporting of image data (whichmay or may not be color corrected) to an external general purposecomputer or special purpose computer.

The processing system 3103 also responds to user commands (e.g., acommand to “take” a picture or capture video by capturing image(s) onthe image sensor and storing the image(s) in memory or a command toselect an option for contrast enhancement and color balance adjustment).

The ROM 3157 may store software instructions for execution by theprocessing system 3103 to enter an image capture mode, continuouslycapture and display images, continuously store the sequence of images ina buffer, automatically select one of the buffered images, andautomatically display the selected image. The storage device 3104 isused to store captured/recorded images which are received from the imagesensor 3159. It will be appreciated that other alternative architecturesof a camera can be used with the various embodiments of the invention.

Battery 3107 may be, for example, a rechargeable or non-rechargeablelithium or nickel metal hydride battery. Wireless device 3100 may alsoinclude audio transducers 3108, which may include one or more speakers,and at least one microphone 3105A, an accelerometer 2846, and a motionsensor 340 (e.g., an accelerometer, a gyroscrope, a motion detector, atilt sensor such as mercury switch, a compass, or any combinationthereof) to determine motion information for the device. The processingsystem is configured to determine whether the device is moving based onthe motion information. More details regarding motion sensors and use ofthe motion information for image capturing devices can be found inapplication publication no. US 2010/0309334, filed Jun. 5, 2009,entitled “Camera Image Selection Based on Detected Device Movement”which is incorporated by reference in entirety herein.

In some embodiments, the image capturing device 3100 includes thestorage device 3104 to store captured images, the lens 3163 to receiveincident light associated with an image to be captured, and theprocessing system 3103 coupled to the storage device 3104 and the lens3163. The device also includes a display device 3106 coupled to thestorage device 3104. The display device can display the captured images.

The processing system 3103 can be configured, after entry into a mode,to continuously capture images, to store a predetermined number of thesequence of images in a buffer, to receive a user request to capture animage, and in response to the user request, automatically selecting oneof the buffered images based on an image contrast parameter thatcompares pixel values within each buffered image. In an embodiment, thebuffer may be located in the system 3100 or in the unit 3160. Thesequence of images may be captured just prior to receiving the userrequest. The processing system 3103 while automatically selecting one ofthe buffered images based on the image contrast parameter is furtherconfigured to determine a focus score for a focus area of each bufferedimage.

The processing system 3103 also can be configured to automaticallyselect one of the buffered images which were all captured prior toreceiving the user request. In an embodiment, the sequence of images caninclude only images captured just prior to receiving the user request totake a photograph. In one embodiment, the sequence of images stored inthe storage device can include the three images captured by the imagecapturing device just prior to receiving the user request.

In some embodiments of the present disclosure, the wireless device 3100can be used to implement at least some of the methods discussed in thepresent disclosure.

FIG. 7 shows an example of a data processing system according to anembodiment of the present invention. This data processing system 3200may include a processing system 3202, and a memory 3204, which arecoupled to each other through a bus 3206. The data processing system3200 may optionally include a cache 3208 which is coupled to theprocessing system 3202. The data processing system may optionallyinclude a storage device 3240 which may be, for example, any type ofsolid-state or magnetic memory data processing system. Storage device3240 may be or include a machine-readable medium.

This data processing system may also optionally include a displaycontroller and display device 3210 which is coupled to the othercomponents through the bus 3206. One or more input/output controllers3212 are also coupled to the bus 3206 to provide an interface forinput/output device 3214 and to provide an interface for one or moresensors 3216 which are for sensing user activity. The bus 3206 mayinclude one or more buses connected to each other through variousbridges, controllers, and/or adapters as is well known in the art. Theinput/output devices 3214 may include a keypad or keyboard or a cursorcontrol data processing system such as a touch input panel. Furthermore,the input/output devices 3214 may include a network interface which iseither for a wired network or a wireless network (e.g. an RFtransceiver). The sensors 3216 may be any one of the sensors describedherein including, for example, a proximity sensor or an ambient lightsensor. In at least certain implementations of the data processingsystem 3200, the processing system 3202 may receive data from one ormore sensors 3216 or from image sensor 3259 or from accelerometer 3246and may perform the analysis of that data in the manner describedherein. Image sensor 3259 captures an image via light focused by lens3263.

In certain embodiments of the present disclosure, the data processingsystem 3200 can be used to implement at least some of the methodsdiscussed in the present disclosure.

In some embodiments, the data processing system 3200 includes a storagedevice 3240 to store a plurality of captured images and a lens coupledto the storage device. The lens receives light associated with thecaptured images and focuses the light onto an image sensor 3259. Thesystem 3200 also includes a display device 3210 that displays imagescaptured by the sensor 3259.

In some embodiments, the processing system is configured to continuouslycapture a sequence of images; to store a predetermined number of thesequence of images in a buffer, to receive a user request to capture animage; and to automatically select one of the buffered images based onan exposure time of one of the buffered images. The sequence of imagesmay be captured prior to or concurrently with receiving the userrequest. In embodiments, the buffer may be located in the system 3202 orthe cache 3208 or memory 3204 or integrated with the image sensor 3259and associated processing circuitry.

The processing system while automatically selecting one of the bufferedimages is further configured to determine an exposure time of one of thebuffered images, determine whether the exposure time meets predeterminedcriteria based on a predetermined threshold exposure time, and selectthe most recent image if the exposure time meets the predeterminedcriteria. The processing system is also configured to initiate thecontinuously capturing and the storing after the data processing systementers an image capture mode.

The processing system while automatically selecting one of the bufferedimages is further configured to determine a focus score for eachbuffered image and to select a buffered image based on the focus scoreif the exposure time fails to meet the predetermined criteria. Theprocessing system while selecting a buffered image based on the focusscore is further configured to determine a product of the focus scoreand the weighted factor for each of the buffered images and select abuffered image having a highest product if the exposure time fails tomeet the predetermined criteria.

The methods of the present invention can be implemented using dedicatedhardware (e.g., using Field Programmable Gate Arrays, or ApplicationSpecific Integrated Circuit, which many be integrated with image sensors(e.g., CCD or CMOS) or shared circuitry (e.g., microprocessors ormicrocontrollers under control of program instructions stored in amachine readable medium, such as memory chips) for an imaging device.The methods of the present invention can also be implemented as computerinstructions for execution on a data processing system.

In the foregoing specification, the invention has been described withreference to specific exemplary embodiments thereof. It will be evidentthat various modifications may be made thereto without departing fromthe broader spirit and scope of the invention as set forth in thefollowing claims. The specification and drawings are, accordingly, to beregarded in an illustrative sense rather than a restrictive sense.

1. A method comprising: continuously capturing a sequence of images withan image capturing device; storing a predetermined number of thesequence of images in a buffer; receiving a user request to capture animage; and in response to the user request, automatically selecting oneof the buffered images based on a comparison of an exposure time of oneof the buffered images and a predetermined threshold exposure time,wherein the sequence of images is captured prior to or concurrently withreceiving the user request.
 2. The method of claim 1, furthercomprising: continuously replacing the images stored in the buffer withnewly captured images.
 3. The method of claim 1: wherein thecontinuously captured images are captured and buffered in fullresolution.
 4. The method of claim 1, wherein the predetermined numberof the sequence of images stored in the buffer comprises three imagescaptured by the image capturing device.
 5. The method of claim 1,wherein automatically selecting one of the the sequence of imagesfurther comprises: determining the exposure time for one of the sequenceof images; and selecting the most recently captured image, which wascaptured just prior to or concurrently with receiving the user request,if the exposure time meets predetermined criteria based on thepredetermined threshold exposure time.
 6. The method of claim 5, furthercomprising: determining a focus score for each captured image; andselecting a buffered image based on the focus score.
 7. The method ofclaim 1, wherein the sequence of images comprise only images capturedjust prior to receiving the user request.
 8. A non-transitory machinereadable medium containing executable computer program instructionswhich when executed by a data processing system cause said system toperform a method, the method comprising: continuously capturing asequence of images with an image capturing device; storing apredetermined number of the sequence of images in a buffer; receiving auser request to capture an image; and in response to the user request,automatically selecting one of the buffered images based on a comparisonof an exposure time of one of the buffered images and a predeterminedthreshold exposure time, wherein the sequence of images is capturedprior to or concurrently with receiving the user request.
 9. The mediumof claim 8, the method further comprising: continuously replacing theimages stored in the buffer with newly captured images.
 10. The mediumof claim 8: wherein the continuously captured images are captured andbuffered in full resolution.
 11. The medium of claim 8, wherein thepredetermined number of the sequence of images stored in the buffercomprises three images captured by the image capturing device.
 12. Themedium of claim 8, wherein automatically selecting one of the thesequence of images further comprises: determining the exposure time forone of the sequence of images; and selecting the most recently capturedimage, which was captured just prior to or concurrently with receivingthe user request, if the exposure time meets predetermined criteriabased on the predetermined threshold exposure time.
 13. The medium ofclaim 12, the method further comprising: determining a focus score foreach captured image; and selecting a buffered image based on the focusscore.
 14. The medium of claim 8, wherein the sequence of imagescomprise only images captured just prior to receiving the user request.15. A data processing system, comprising: a storage device to store aplurality of captured images; a lens coupled to the storage device, thelens to receive light associated with the captured images; a processingsystem coupled to the storage device, the processing system isconfigured to continuously capture a sequence of images; to store apredetermined number of the sequence of images in a buffer; to receive auser request to capture an image; and to automatically select one of thebuffered images based on a comparison of an exposure time of one of thebuffered images and a predetermined threshold exposure time, wherein thesequence of images is captured prior to or concurrently with receivingthe user request.
 16. The data processing system of claim 15, whereinthe processing system while automatically selecting one of the bufferedimages is further configured to: determine an exposure time of one ofthe buffered images; determine whether the exposure time meetspredetermined criteria based on the predetermined threshold exposuretime; and select the most recent image if the exposure time meets thepredetermined criteria and wherein the processing system is configuredto initiate the continuously capturing and the storing after the dataprocessing system enters an image capture mode.
 17. The data processingsystem of claim 16, wherein the processing system while automaticallyselecting one of the buffered images is further configured to: determinea focus score for each buffered image; and selecting a buffered imagebased on the focus score.
 18. The data processing system of claim 17,wherein the processing system while selecting a buffered image based onthe focus score is further configured to: determine a product of thefocus score and the weighted factor for each of the buffered images; andselect a buffered image having a highest product if the exposure timefails to meet the predetermined criteria.
 19. A data processing system,comprising: a storage device to store a plurality of captured images; alens coupled to the storage device, the lens to receive light associatedwith the captured images; a processing system coupled to the storagedevice, the processing system is configured to continuously capture asequence of images; to store a predetermined number of the sequence ofimages in a buffer; to receive a user request to capture an image; andto automatically select one of the buffered images based on an exposuretime of one of the buffered images, wherein the processing system whileautomatically selecting one of the buffered images is further configuredto: determine a focus score for each buffered image; determine a productof the focus score and a weighted factor for each of the bufferedimages; and select a buffered image having a highest product if theexposure time fails to meet a predetermined criteria.
 20. The dataprocessing system of claim 19, wherein the processing system whileautomatically selecting one of the buffered images is further configuredto: determine an exposure time of one of the buffered images; determinewhether the exposure time meets predetermined criteria based on apredetermined threshold exposure time; and select the most recent imageif the exposure time meets the predetermined criteria and wherein theprocessing system is configured to initiate the continuously capturingand the storing after the data processing system enters an image capturemode.